As LSI circuits are increasing in density, the line width of circuits of semiconductor devices is becoming finer. Examples of methods of producing an exposure mask (also called a reticle that is used in a stepper or a scanner) to be used to form a circuit pattern for such a semiconductor device include an electron beam writing technique with high resolution.
A writing apparatus using multiple beams enables irradiation with many beams at a time (in a single shot) as compared with writing with a single electron beam, and thus markedly increases throughput. In such a multi-beam writing apparatus, for example, an electron beam emitted downwardly from an electron gun passes through an aperture member having a plurality of holes, thus forming multiple beams.
Under the aperture member, a blanking plate is disposed which has passage holes aligned with the holes arranged in the aperture member. Each of the passage holes of the blanking plate is provided with an individual blanker (individual blanking deflector) that performs blanking deflection on the corresponding beam.
Under the blanking plate, a common blanker (common blanking deflector) is disposed which collectively performs blanking control on the multiple beams. Under the common blanker, a limiting aperture member having a hole at its central part is disposed. The electron beams deflected in a beam OFF state by the individual blankers or the common blanker are deviated from the central hole of the limiting aperture member, so that the beams are interrupted by the limiting aperture member. The electron beams that are not deflected by the individual blankers and the common blanker pass through the limiting aperture member. The passed beams are deflected by a deflector and are applied at intended positions on a substrate.
In a configuration in which a beam deflection direction of the individual blankers is opposite to a beam deflection direction of the common blanker, when one of the common blanker and the individual blanker deflects the beam to the beam OFF state while the other of the common blanker and the individual blanker deflects the beam in the beam OFF state, the beam passes through the hole of the limiting aperture member, causing the leakage of the beam. This results in insufficient control of the amount of beams applied to a substrate. This leads to a reduction in writing accuracy.